This invention relates to a power transmission chain. In particular, it relates to a power transmission chain with a large number of interleaved links. Each link has a pair of teeth and a pair of apertures. The links are interleaved in rows or sets and are connected by connecting pins.
Silent chains, or inverted tooth chains, are used as power transmission chain for automobiles, motorcycles, and other vehicles. A conventional silent chain, which is shown in FIG. 9, typically consists of large number of links or link plates 50, each having a pair of teeth 51 and a pair of apertures or pinholes 52. The links are interleaved in rows or sets and connected by connecting pins 53, which are inserted in pinholes 52. Each tooth includes an inside flank 51a and an outside flank 5lb, which are joined at the crotch.
During operation of the silent chain, one of the flanks of tooth 51 of link plate 50 engages a tooth of the sprocket for power transmission from the driving sprocket to the driven sprocket. As illustrated in FIG. 10, silent chain 70 forms a polygon by connecting pins 53 that connect the link plates around sprocket 60. In FIG. 10, the solid and broken lines show the positions of the pitch lines of silent chain 70 when sprocket 60 rotates and the rotation phase difference corresponds to the half-period.
Since the silent chain travels in a polygonal motion around the sprocket, the silent chain undertake a chordal motion (up/down motion of the chord or chain strand) of the amplitude .DELTA.T' between the driven and driving sprockets. As a result of study of the noise of silent chains, it is believed that tension fluctuations in the chain occur due to the up/down motion of the chain strand. As a result, the torque of the driven shaft fluctuates, which generates noise.
Additionally, fluctuation of the circumferential speed of the chain occurs due to the up/down motion of the chord, resulting in an angular velocity fluctuations of the driven shaft, which also generates noise.
The present invention is directed to such a conventional situation and its purpose is to offer a power transmission chain that can reduce noise through suppression of chordal up/down motion.